Straight air channel cylinder cover and gas engine

Abstract

The invention relates to the technical field of gas engine cylinder covers, and discloses a straight-air-channel cylinder cover and a gas engine, the straight-air-channel cylinder cover comprises a cylinder cover and two air inlet channels, and the cylinder cover is a flat-top cylinder cover; the two air inlet channels are tumble air channels and communicate with the cylinder cover, the communicating positions of the two air inlet channels and the cylinder cover are arranged in a spaced mode, and the two air inlet channels are gradually close to each other in the direction away from the cylinder cover. The straight air channel cylinder cover can form tumble flow in the cylinder, turbulent kinetic energy of mixed fuel gas is improved, the combustion speed is increased, and the heat efficiency of the whole machine is improved; and the two air inlet channels are arranged in a V shape, and after mixed gas enters the air cylinder, flames have the trend of diffusing towards the two ends of the tumble axis, so that the flames can rapidly fill a combustion chamber along with tumble movement, the combustion speed is increased, and the heat efficiency of the whole machine is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of gas engine cylinder heads, and in particular to a straight-airway cylinder head and a gas engine. Background Art

[0002] Heavy-duty gas engines are ignition-type internal combustion engines, similar to gasoline engines. Their combustion form requires the organization of a certain intensity of tumble flow in the cylinder, but most of the heavy-duty gas engines (including natural gas and hydrogen) at home and abroad in the National VI stage are modified from diesel engines.

[0003] However, most of the heavy-duty gas engines at home and abroad in the National VI stage are modified from diesel engines. The intake duct is a vortex air duct, and the turbulent kinetic energy in the cylinder is low at the time of ignition. At the same time, large-scale vortices will lead to an increased tendency to knock, which is not conducive to improving thermal efficiency. Summary of the invention

[0004] The purpose of the present invention is to overcome the above technical deficiencies, and to provide a straight airway cylinder head and a gas engine, so as to solve the technical problems in the prior art that the use of vortex airways in gas engines can lead to low turbulent kinetic energy and detonation.

[0005] In order to achieve the above technical objectives, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a straight channel cylinder head, comprising: Cylinder head, which is a flat top cylinder head; Two intake ducts are tumble flow ducts and are connected to the cylinder head. The connecting parts of the two intake ducts and the cylinder head are arranged at intervals, and the two intake ducts gradually approach each other in a direction away from the cylinder head.

[0006] In one embodiment, the intake passage comprises a first inclined air passage, an arc guide air passage and a second inclined air passage which are connected in sequence along a direction close to the cylinder head, and the slope of the first inclined air passage is smaller than the slope of the second inclined air passage.

[0007] In one embodiment, there is a first center plane between the two intake ducts, the first center plane passes through the axis of the cylinder head, and in the projection of the intake duct on the first center plane, the side of the intake duct close to the cylinder head has a first straight line segment, a first arc segment and a second straight line segment connected in sequence, the range of the angle θ2 between the first straight line segment and the top surface of the cylinder head is 0° to 15°, the range of the angle R1 of the first arc segment is 80 mm to 100 mm, and the range of the angle θ1 between the second straight line segment and the top surface of the cylinder head is 40° to 60°; The side of the intake duct away from the cylinder head has a third straight segment, a second arc segment and a fourth straight segment connected in sequence, the angle θ4 between the third straight segment and the top surface of the cylinder head is in the range of 20° to 40°, the angle R2 of the second arc segment is in the range of 80 mm to 100 mm, and the angle θ3 between the fourth straight segment and the top surface of the cylinder head is in the range of 30° to 50°.

[0008] In one embodiment, the two exhaust passages are symmetrically distributed along the first center plane.

[0009] In one of the embodiments, two exhaust passages are further included, the two exhaust passages are connected to the cylinder head, and the connecting parts are arranged at intervals, and the two exhaust passages gradually approach each other in a direction away from the cylinder head.

[0010] In one embodiment, the two exhaust passages are symmetrically distributed along the first center plane.

[0011] In one embodiment, a second center plane is defined between the two intake passages and the two exhaust passages, the second center plane passes through the axis of the cylinder head, and the intake passages and the exhaust passages are symmetrically distributed along the second center plane.

[0012] In one embodiment, the two air inlet ducts share one air inlet port, and the side walls of the air inlet ends of the two air inlet ducts are provided with communicating openings.

[0013] In one embodiment, the projection of the intake passage on the top surface of the cylinder head is arc-shaped.

[0014] In a second aspect, the present invention further provides a gas engine, comprising the straight-channel cylinder head as described above.

[0015] Compared with the prior art, the straight-port cylinder head and gas engine provided by the present invention, during the intake stroke of the gas engine, the mixed gas enters the cylinder through the intake manifold and the intake port, and when the mixed gas passes through the intake port, the intake port organizes the flow field of the mixed gas, and cooperates with the combustion chamber to form an airflow movement that affects combustion, and after the mixed gas enters the cylinder through the tumble flow port, under the condition of a non-dome design, a mixed gas flow field with a certain tumble ratio can be formed in the cylinder, thereby increasing the turbulent kinetic energy near the spark plug electrode, and after the spark plug is ignited, the fire core diffuses outward at the spark plug electrode position, and the flame can quickly fill the combustion chamber with the tumble movement, thereby accelerating the combustion speed and improving the thermal efficiency of the whole machine.

[0016] Moreover, the present invention is based on the diesel engine flat-top cylinder head, and the vortex airway is modified into a tumble airway, so that the airflow organization forms a tumble flow in the cylinder; the cylinder head can be directly modified from the diesel engine, and the production assembly line can directly adopt the diesel engine matching, with low investment cost. Under the premise that the cylinder head still keeps the boundary unchanged, through the airway structure design, the tumble flow in the cylinder is organized, the turbulent kinetic energy in the cylinder is increased, the flame front propagates faster in the cylinder, the combustion speed is accelerated, and the thermal efficiency of the engine is improved.

[0017] Compared with the traditional vortex airway, the tumble flow generated by the airway of the proposed proposal has higher turbulent kinetic energy, which is conducive to promoting oil-gas mixing, improving combustion speed and thermal efficiency. Under certain conditions, high tumble can further improve thermal efficiency, especially in achieving ultra-high thermal efficiency. At the same time, the flat-top design focuses more on forming a uniform mixture rather than a strong tumble flow, which is more suitable for the premixed combustion of natural gas, which means that the cycle variation is smaller, so the stability and durability of the engine are better. For in-cylinder combustion, the tumble intake port is conducive to spark plug scavenging, which can improve the ignition environment of the spark plug, thereby shortening the ignition delay period, causing early ignition, increased cylinder pressure and reduced cycle variation. At the moment of ignition, the turbulent kinetic energy generated by the tumble airway is significantly improved relative to the vortex airway. In terms of airflow organization, the intake port of the present invention basically does not generate vortex, but forms a certain level of tumble flow. For natural gas engines, the thermal efficiency is significantly improved at the same compression ratio. At the same time, the compression ratio increase of the traditional scheme is limited by detonation, while the scheme of the present invention can adopt a higher compression ratio to achieve higher thermal efficiency.

[0018] At the same time, compared with the solution in which two intake ducts are arranged in parallel, after the mixture enters the cylinder through the two parallel intake ducts, the tumble is located in the middle of the cylinder, and the flame diffuses slowly to the surroundings, resulting in incomplete combustion; whereas in the present invention, the two intake ducts gradually approach each other in the direction away from the cylinder head, resulting in the two intake ducts being arranged in a V-shape. After the mixture enters the cylinder, the flame has a tendency to diffuse toward both ends of the tumble axis, so that the flame can quickly fill the combustion chamber with the tumble motion, thereby accelerating the combustion speed and further improving the thermal efficiency of the whole machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic structural diagram of a straight airway cylinder head provided by an embodiment of the present invention; Figure 2 is a schematic structural diagram of a straight airway cylinder head provided by an embodiment of the present invention; Figure 3 It is a streamline diagram of the airflow in the cylinder head in the prior art; Figure 4 is a streamline diagram of airflow of a straight-channel cylinder head provided by an embodiment of the present invention; Figure 5The figure is a comparison diagram of thermal efficiency between a straight-channel cylinder head provided by an embodiment of the present invention and a cylinder head in the prior art.

[0020] Description of reference numerals: Cylinder head 1; intake duct 2; exhaust duct 3; first center plane 4; second center plane 5; intake port 6; exhaust port 7; combustion chamber 8. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0022] At present, natural gas engines are mainly modified and matched based on the existing diesel engine platform. One of the key components, the cylinder head, usually retains the structure of the original diesel engine's vortex cylinder head. This design method aims to utilize mature diesel engine technology to reduce development costs and time; but this means that the airway also retains the vortex airway. The vortex airway has low turbulent kinetic energy in the cylinder during ignition, and large-scale vortices will increase the tendency of knocking, which is not conducive to improving thermal efficiency.

[0023] Natural gas engines are spark-ignited, just like gasoline engines, and gasoline engines all have dome tumble flow passages. Tumble flow is a rotational motion perpendicular to the cylinder axis. This motion is crushed by the piston at the top dead center and is highly unstable, but it can increase the turbulent kinetic energy in the cylinder and help improve the combustion process. However, there are problems with the use of dome tumble flow passages. The dome tumble flow passages cause the valve to be tilted. After the valve is tilted, the engine cannot be remodeled based on the diesel engine. At the same time, a new cylinder head processing line and engine assembly line need to be built, and the initial investment in industrialization is huge. In addition, the tumble flow generated by the dome is relatively large, and strong tumble flow may lead to increased cycle changes, affecting the stability and durability of the engine.

[0024] In order to solve the technical problem that the use of vortex air duct in a gas engine will lead to low turbulent kinetic energy and detonation, the present invention provides a straight air duct cylinder head and a gas engine, which can solve the technical problem of low turbulent kinetic energy and detonation in the gas engine in the prior art.

[0025] It should be noted that the straight-channel cylinder head described in the present invention is used for but not limited to gas engines, etc. For the convenience of explanation, in the present invention, only the straight-channel cylinder head applied to a gas engine is used as an example for explanation, and the principle of applying the straight-channel cylinder head to other types of equipment is essentially the same as that applied to a gas engine, which will not be described in detail here.

[0026] See also Figure 1 , Figure 1Schematic diagram of the structure of a straight-channel cylinder head in one embodiment of the present invention, a straight-channel cylinder head, including a cylinder head 1 and two intake passages 2, the cylinder head 1 is a flat-top cylinder head; the two intake passages 2 are tumble passages, and are connected to the cylinder head 1, the connecting parts of the two intake passages 2 and the cylinder head 1 are arranged at intervals, and the two intake passages 2 gradually approach each other in the direction away from the cylinder head 1.

[0027] Specifically, Figure 4 As shown, during the intake stroke of the gas engine, the mixed gas enters the cylinder through the intake manifold and the intake duct 2. When the mixed gas passes through the intake duct 2, the intake duct 2 organizes the flow field of the mixed gas and cooperates with the combustion chamber to form an airflow movement that affects combustion. After the mixed gas enters the cylinder through the tumble flow duct, under the condition of non-dome design, a mixed gas flow field with a certain tumble ratio can be formed in the cylinder to increase the turbulent kinetic energy near the spark plug electrode. Turbulent motion is different from eddy current. It is a multi-directional, irregular tiny vortex generated in high-speed airflow, which plays a decisive role in optimizing the combustion process. Turbulent motion is crucial to the formation of flame folds, which helps to speed up the propagation speed of the flame and thus improve the thermal efficiency of the engine. After the spark plug is ignited, the fire core spreads outward at the spark plug electrode position, and the flame can quickly fill the combustion chamber with the tumble motion, thereby speeding up the combustion speed and improving the thermal efficiency of the whole machine.

[0028] Moreover, the present invention is based on a diesel engine flat-top cylinder head, and modifies the vortex airway into a tumble airway, so as to achieve airflow organization to form tumble flow in the cylinder, thereby avoiding a series of problems existing in the vortex cylinder head of a diesel engine; the cylinder head 1 can be directly modified from a diesel engine, and the production assembly line can directly adopt a diesel engine matching, with low investment cost. Under the premise that the cylinder head 1 still maintains the boundary unchanged, through the airway structure design, the tumble flow in the cylinder is organized, the turbulent kinetic energy in the cylinder is increased, the flame front propagates faster in the cylinder, the combustion speed is accelerated, and the thermal efficiency of the engine is improved.

[0029] Compared with the traditional vortex airway, the tumble flow generated by the airway in this proposal has higher turbulent kinetic energy, which is conducive to promoting oil-gas mixing, improving combustion speed and thermal efficiency. Under certain conditions, high tumble flow can further improve thermal efficiency, especially in achieving ultra-high thermal efficiency. At the same time, the flat-top design focuses more on forming a uniform mixture rather than strong tumble flow, which is more suitable for the premixed combustion of natural gas, which means that the cycle changes are smaller, so the stability and durability of the engine are better.

[0030] For in-cylinder combustion, the intake duct 2 of the tumble flow channel is beneficial to spark plug scavenging, which can improve the ignition environment of the spark plug, thereby shortening the ignition delay period, causing early ignition, increased in-cylinder pressure, and reduced cyclic variation. At the moment of ignition, the turbulent kinetic energy generated by the intake duct 2 of the tumble flow channel is significantly improved relative to the vortex flow channel. In terms of airflow organization, the intake duct 2 of the present invention basically does not generate vortices, but forms a certain level of tumble flow. For natural gas engines, the thermal efficiency is significantly improved at the same compression ratio. At the same time, the compression ratio improvement of the traditional scheme is limited by detonation, while the scheme of the present invention can adopt a higher compression ratio to achieve higher thermal efficiency.

[0031] At the same time, compared with the scheme in which the two intake ducts 2 are arranged in parallel, in the scheme in which the two intake ducts 2 are arranged in parallel, after the mixture enters the cylinder through the two parallel intake ducts 2, the tumble is located in the middle of the cylinder, and the flame diffuses slowly along the axis of the tumble, resulting in incomplete combustion; while in the present invention, the two intake ducts 2 gradually approach each other in a direction away from the cylinder head 1, resulting in the two intake ducts 2 being arranged in a V-shape. After the mixture enters the cylinder, the flame has a tendency to diffuse toward both ends of the tumble axis, so that the flame can quickly fill the combustion chamber with the tumble movement, thereby accelerating the combustion speed and further improving the thermal efficiency of the whole machine.

[0032] like Figure 1 As shown, in one of the embodiments, a first center plane 4 is provided between the two intake passages 2 , the first center plane 4 passes through the axis of the cylinder head 1 , and the two intake passages 2 are symmetrically distributed along the first center plane 4 .

[0033] Through the above arrangement, the two intake passages 2 are symmetrically distributed along the first center plane 4, and the flow path and flow velocity of the mixed gas entering the cylinder through the two intake passages 2 are the same, so that the tumble flow formed in the cylinder is more stable and can flow toward the set path, thereby improving the intake efficiency and the quality and stability of the formation of the mixed gas.

[0034] like Figure 1 As shown, in one of the embodiments, the straight-channel cylinder head further includes two exhaust passages 3 , which are connected to the cylinder head 1 , and the connecting parts are arranged at intervals, and the two exhaust passages 3 gradually approach each other in a direction away from the cylinder head 1 .

[0035] The configuration of the exhaust duct 3 matches that of the intake duct 2, which reduces the resistance during the exhaust process, increases the exhaust speed of the exhaust gas, reduces the amount of residual exhaust gas, and facilitates better entry of the mixed fuel gas.

[0036] like Figure 1 As shown, in one embodiment, two exhaust passages 3 share one exhaust port 7 , and two exhaust passages 3 are connected with each other at the exhaust port 7 .

[0037] In this embodiment, the two exhaust passages 3 share one exhaust port 7, which can increase the exhaust flow rate and reduce the exhaust resistance.

[0038] like Figure 1 As shown, in one embodiment, the two exhaust passages 3 are symmetrically distributed along the first center plane 4 .

[0039] The two exhaust passages 3 are symmetrically arranged, so that the exhaust paths and exhaust flow fields of the two exhaust passages 3 are the same, and the exhaust gas can enter the exhaust passage 3 from the cylinder at the same angle and path, and the exhaust gas is more stable.

[0040] like Figure 1 As shown, in one embodiment, there is a second center plane 5 between the two intake passages 2 and the two exhaust passages 3 , the second center plane 5 passes through the axis of the cylinder head 1 , and the intake passages 2 and the exhaust passages 3 are symmetrically distributed along the second center plane 5 .

[0041] Through the above arrangement, the tumble center of the mixed gas formed in the cylinder is closer to the middle of the cylinder. When the mixed gas is mixed, the flame can spread outward from the center, so that the gas in different parts of the cylinder can burn quickly. At the same time, after the mixed gas is burned, the distance it enters the two exhaust ducts 3 is the same, avoiding different exhaust pressures on both sides of the exhaust duct 3, making the intake and exhaust processes more uniform, which helps to reduce knocking during the combustion process.

[0042] As the two intake ducts 2 gradually approach each other in the direction away from the cylinder head 1, the distance between the two intake ducts 2 will gradually decrease. In order to arrange the two intake ducts 2 at a preset angle within a limited space, in one of the embodiments, the two intake ducts 2 share an intake port 6, and the side walls of the intake ends of the two intake ducts 2 are provided with interconnected openings.

[0043] Through the above arrangement, the two air intake passages 2 share one air intake port 6, so that the two air intake passages 2 can be installed in a limited space. At the same time, using one air intake port 6 can increase the upper limit of the intake air flow rate.

[0044] Since the intake duct 2 shares an intake port 6, there is a distance between the intake port 6 of the intake duct 2 and the outlet end of the intake duct 2 along the radial direction of the cylinder. Figure 1 As shown, in one of the embodiments, the projection of the intake passage 2 on the top surface of the cylinder head 1 is arc-shaped.

[0045] By setting the projection of the intake duct 2 on the top surface of the cylinder head 1 to be arc-shaped, the intake duct 2 can enter the cylinder in an arc-shaped manner. The arc-shaped intake duct 2 can guide the mixed gas to enter from the intake port of the intake duct 2 in an arc-shaped manner, and enter the cylinder from the exhaust port of the intake duct 2, avoiding corners in the intake path and reducing intake damping.

[0046] In order to form a tumble flow passage in the intake passage 2, for this purpose, Figure 2 As shown, in one embodiment, the intake passage 2 has a first inclined air passage, an arc guide air passage and a second inclined air passage which are connected in sequence along a direction close to the cylinder head 1, and the slope of the first inclined air passage is smaller than the slope of the second inclined air passage.

[0047] After the mixed gas enters the intake duct 2, it first enters the first inclined air duct with a small angle, and then is smoothly transitioned to the second inclined air duct with a large angle through the arc guide air duct. Through the lower part of the intake duct 2, the tangent cylinder wall with a large angle, the mixed gas enters the cylinder from the position of the intake duct 2, and impacts the exhaust duct 3 from the upper part of the cylinder. The airflow rotates in the diagonal vertical direction, and its rotation center tends to the center of the cylinder, and the rotation axis is perpendicular to the cylinder axis, that is, tumble motion.

[0048] In order to form the first inclined airway, the arc guide airway and the second inclined airway in the air intake 2, it is specifically obtained as follows: Figure 2 As shown, in one of the embodiments, in the projection of the intake duct 2 on the first center plane 4, the side of the intake duct 2 close to the cylinder head 1 has a first straight line segment, a first arc segment and a second straight line segment connected in sequence, the angle θ2 between the first straight line segment and the top surface of the cylinder head 1 is in the range of 0° to 15°, the angle R1 of the first arc segment is in the range of 80 mm to 100 mm, and the angle θ1 between the second straight line segment and the top surface of the cylinder head 1 is in the range of 40° to 60°; the side of the intake duct 2 away from the cylinder head 1 has a third straight line segment, a second arc segment and a fourth straight line segment connected in sequence, the angle θ4 between the third straight line segment and the top surface of the cylinder head 1 is in the range of 20° to 40°, the angle R2 of the second arc segment is in the range of 80 mm to 100 mm, and the angle θ3 between the fourth straight line segment and the top surface of the cylinder head 1 is in the range of 30° to 50°.

[0049] Among them, the area of ​​the inner wall between the first straight line segment and the third straight line segment is the first inclined airway, the area of ​​the inner wall between the first arc segment and the second arc segment is the arc guide airway, and the area of ​​the inner wall between the second straight line segment and the fourth straight line segment is the second inclined airway.

[0050] Specifically, Figure 2 As shown, in one embodiment, the angle θ2 between the first straight line segment and the top surface of the cylinder head 1 is 7.5°, the angle R1 of the first arc segment is in the range of 90 mm, and the angle θ1 between the second straight line segment and the top surface of the cylinder head 1 is in the range of 50°; the side of the intake duct 2 away from the cylinder head 1 has a third straight line segment, a second arc segment and a fourth straight line segment connected in sequence, the angle θ4 between the third straight line segment and the top surface of the cylinder head 1 is in the range of 30°, the angle R2 of the second arc segment is in the range of 90 mm, and the angle θ3 between the fourth straight line segment and the top surface of the cylinder head 1 is in the range of 40°.

[0051] like Figures 3 to 5 As shown, the thermal efficiency of the air intake duct 2 formed by the above-mentioned dimensions is much higher than the thermal efficiency of the gas engine in the prior art.

[0052] In a second aspect, the present invention further provides a gas engine, comprising the straight-channel cylinder head as described above. Since the engine adopts the straight-channel cylinder head in the above embodiment, the technical effect of the gas engine please refer to the above embodiment.

[0053] The mixed fuel gas of the gas engine may be natural gas, hydrogen, or a combination of more than one of the above.

[0054] like Figure 2 As shown, in one embodiment, a combustion chamber 8 is formed between the top of the gas engine and the cylinder head, and the combustion chamber 8 is cylindrical and has a spherical bottom. When the mixed gas flows through the spherical surface at the bottom of the combustion chamber 8, it can flow along the guide of the spherical surface to form a tumble flow in the combustion chamber 8, and can cooperate with the straight-channel cylinder head to strengthen the tumble flow in the cylinder during the intake and compression strokes, thereby increasing the combustion speed and reducing fuel consumption.

[0055] It should be understood that the number of straight-channel cylinder heads in the gas engine may be one, two, or more. When the number of straight-channel cylinder heads in the gas engine is more than one, the multiple straight-channel cylinder heads are arranged in parallel.

[0056] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0057] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0058] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific conditions.

[0059] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0060] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A straight channel cylinder head, characterized in that: include: The cylinder head is a flat top cylinder head; Two intake ducts are tumble flow ducts and are connected to the cylinder head. The connecting parts of the two intake ducts and the cylinder head are arranged at intervals, and the two intake ducts gradually approach each other in a direction away from the cylinder head.

2. The straight channel cylinder head according to claim 1, characterized in that: The intake passage has a first inclined air passage, an arc guide air passage and a second inclined air passage which are connected in sequence along a direction close to the cylinder head, and the slope of the first inclined air passage is smaller than the slope of the second inclined air passage.

3. The straight channel cylinder head according to claim 2, characterized in that: There is a first center plane between the two intake ducts, the first center plane passes through the axis of the cylinder head, and in the projection of the intake duct on the first center plane, the side of the intake duct close to the cylinder head has a first straight line segment, a first arc segment and a second straight line segment connected in sequence, the range of the angle θ2 between the first straight line segment and the top surface of the cylinder head is 0° to 15°, the range of the angle R1 of the first arc segment is 80 mm to 100 mm, and the range of the angle θ1 between the second straight line segment and the top surface of the cylinder head is 40° to 60°; The side of the intake duct away from the cylinder head has a third straight segment, a second arc segment and a fourth straight segment connected in sequence, the angle θ4 between the third straight segment and the top surface of the cylinder head is in the range of 20° to 40°, the angle R2 of the second arc segment is in the range of 80 mm to 100 mm, and the angle θ3 between the fourth straight segment and the top surface of the cylinder head is in the range of 30° to 50°.

4. The straight channel cylinder head according to claim 3, characterized in that: The two air inlets are symmetrically distributed along the first center plane.

5. The straight channel cylinder head according to claim 3, characterized in that: It also includes two exhaust passages, which are connected to the cylinder head and are arranged at intervals at the connecting points. The two exhaust passages gradually approach each other in a direction away from the cylinder head.

6. The straight channel cylinder head according to claim 5, characterized in that: The two exhaust passages are symmetrically distributed along the first center plane.

7. The straight channel cylinder head according to claim 5, characterized in that: A second center plane is defined between the two intake passages and the two exhaust passages. The second center plane passes through the axis of the cylinder head. The intake passages and the exhaust passages are symmetrically distributed along the second center plane.

8. The straight channel cylinder head according to claim 1, characterized in that: The two air inlet passages share one air inlet port, and the side walls of the air inlet ends of the two air inlet passages are provided with communicating openings.

9. The straight channel cylinder head according to claim 1, characterized in that: The projection of the intake passage on the top surface of the cylinder head is arc-shaped.

10. A gas engine, characterized in that: It comprises a straight-port cylinder head as claimed in any one of claims 1 to 9.

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